Thermal characteristics of a hertfordshire frost‐hollow

Hawke, E. L.

doi:10.1002/qj.49707030306

Cited by 11 publications

(6 citation statements)

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“…Lareau et al ., ) or enclosed basins (Whiteman et al ., ). Hawke () took long‐term observations from 1929 to the mid‐1940s in the Rickmansworth valley in Hertfordshire, characterising the frost hollow in the valley. Galvin (; ) revisited the Rickmansworth valley and identified the change in the valley climate as a result of increased urbanisation since the 1940s.…”

Section: Introductionmentioning

confidence: 99%

A short climatological study of cold air pools and drainage flows in small valleys

Jemmett-Smith

Ross

Sheridan

2018

Weather

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This paper uses detailed observations from the COLd air Pooling EXperiment (COLPEX) to study the frequency and characteristics of cold air pooling in a small‐scale valley typical of much of the southern UK and other lowland regions of the world. The field experiment took place in and around the Clun Valley, Shropshire, England during July 2009–April 2010, which was a particularly cold winter with a record low in the NAO index. Cold pools, defined here as where the minimum valley temperature overnight is at least 1°C colder than the surrounding hilltops, occur on 45% of nights over the observational period, with strong cold pools (>4°C temperature difference) occurring on 12% of nights. As might be expected, cold pool formation is closely linked to conditions with clear skies and light winds, and is often associated with high pressure situations. Cold pools are also closely linked with weak down‐valley drainage flows. This contrasts with non‐cold pool nights or daytime conditions where several other mechanisms also contribute to the observed winds in the valley. The dataset highlights the importance of cold air pools and drainage flows, even in quite moderate terrain, and the impact this can have on local microclimates.

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Section: Introductionmentioning

confidence: 99%

A short climatological study of cold air pools and drainage flows in small valleys

Jemmett-Smith

Ross

Sheridan

2018

Weather

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“…The study demonstrated topographical variation in the frequency of yellow‐shelled snails, and related this to the well‐known phenomenon of temperature inversions, causing valley bottoms to be subject to extreme cold in anticyclonic winter weather. Rickmansworth was the site of an early demonstration of the power of this effect (Hawke, 1944). As with other studies, however, the effect of climate was claimed on the basis of a static association alone.…”

Section: Introductionmentioning

confidence: 99%

Variation in Cepaea populations over 42 years: climate fluctuations destroy a topographical relationship of morph-frequencies

Cameron

Pokryszko²

2008

Biological Journal of the Linnean Society

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Cepaea hortensis (Gastropoda: Pulmonata) populations in Hertfordshire, England, originally sampled in 1964-66, and sampled again in 1990, were sampled in 2007. Although the general pattern of shell colour and banding polymorphism remained stable, a significant trend for a reduction in the frequency of yellow shells in sites from valley bottoms, as observed in 1990, continued through to 2007. In both 1964-66 and 1990, populations in valley bottoms had higher frequencies of yellow shells than those on the sides, but this topographical relationship had effectively disappeared by 2007. The relationship had been explained in terms of low temperature extremes in valley bottoms in cold, anticyclonic conditions. Its decay is associated with much warmer winter conditions prevailing in the 3 years previous to both resurveys, compared with those before the original survey. The frequency of unbanded shells also increased over the period, but this change showed no topographical variation, and thus it is not possible to assign it to a particular cause. The low levels of variation between samples from the same habitat and the absence of present topographical relationships conceal the occurrence of powerful climatic selection, which is revealed only by repeated surveys. The conditions in which such changes might be detected are discussed.

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“…list present opportunities for comparison. With regard to the exceptionally frosty propensities observed in certain dry valleys of limited area, we may refer to the work of our Honorary Secretary Mr. E. L. Hawke, in the remarkable frost-hollow a t Rickmansworth (Hawke, 1933 and1944). But even the average river valley, especially if I t I S somewhat incised, pre.sents noteworthy results.…”

Section: Variations In the Length Of The Frost-free Season 181mentioning

confidence: 95%

Variations in the length of the frost‐free season

Manley¹

1946

Quart J Royal Meteoro Soc

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Thermal characteristics of a hertfordshire frost‐hollow

Abstract: Records of temperature over a 13-year period in a Hertfordshire \alley which has been described as possessing the most " continental " thermal climate yet investigated instrumentally in the British Isles are sumniarised, discussed, and compared with data from other

Cited by 11 publications

References 0 publications

A short climatological study of cold air pools and drainage flows in small valleys

A short climatological study of cold air pools and drainage flows in small valleys

Variation in Cepaea populations over 42 years: climate fluctuations destroy a topographical relationship of morph-frequencies

Variations in the length of the frost‐free season

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